Menthol has been broadly used for a long time because of its characteristics in that it has a special cool fragrance or flavor and can provide refresh-feeling. Presently, it is frequently used in the field of a lip cream or the like fragrance or cosmetic, a compounding agent of a pharmaceutical agent which alleviates muscular ache and the like symptoms, and the like.
Menthol is naturally extracted from peppermint oil of a mint which is a perennial plant of Lamiaceae. On the other hand, methods for chemically synthesizing menthol have also been actively studied and developed, and a large number of synthesizing methods are known.
Menthol is kept in the form of a powdery, a granular, a flake-like, a pellet-like and a stick-like and the like shapes, and as occasion demands, pulled out from the keeping place and blended in a product. In that case, there is a problem of causing spoilage of its handling property due to aggregation of menthol at the time of its keeping, so that concern has been directed toward the development of techniques for solving the problem. As one of such techniques, a technique for applying a compression treatment to menthol under a compression pressure of 50 kN has been reported (Patent Reference 1). It may be said that this method is surely excellent in terms of aggregation or caking, in comparison with the case of the compression-untreated menthol, but it is not at a degree which is sufficiently satisfactory. Particularly, this was not sufficient for satisfying thermal stability during summer season. In addition, since a compressor is used, this is economically disadvantageous in terms of its purchase, maintenance, management and the like, and its operational troublesomeness also remains.    Patent Reference 1: JP-T-2005-528436 (the term “JP-T” as used herein means a published Japanese translation of a PCT patent application)